Dynamics of microglial cells in the brain of Ihara epileptic rats in accordance with seizure progress

阐明癫痫突变体Ihara癫痫大鼠脑胶质细胞增生的定位和程度，可能有助于揭示癫痫脑胶质细胞反应的意义。本文用OX-42抗体免疫组化法研究了小胶质细胞在癫痫发作大鼠IER脑内的定位和反应程度，探讨了小胶质细胞在癫痫发作中的可能功能。在IERS和非癫痫对照大鼠的大脑皮层、鼻内皮层、丘脑、杏仁核、海马和齿状回中，OX-42阳性反应的小胶质细胞密度在IERS（2月龄）大鼠的上述脑部分中轻度或中度增加，特别是在海马、丘脑和杏仁核中。在6个月和10个月大的大鼠中，除全脑外，海马、丘脑和杏仁核中的OX-42阳性小胶质细胞也明显增加。OX-42阳性反应的小胶质细胞具有短而粗的突起，被认为是一种变形虫型的活化小胶质细胞，提示IER脑内小胶质细胞的活化是由癫痫活动引起的，活化的胶质细胞释放的细胞因子对神经元或胶质细胞的功能有一定的影响。由于海马、丘脑和杏仁核等部位的小胶质细胞从幼年开始就被激活，这些区域被认为在癫痫的发生中起着重要作用。此外，从IER全脑OX-42阳性细胞弥漫性增加的发现，可以安全地假设癫痫活动不仅影响海马、丘脑和杏仁核，而且影响脑的其他部分。

It is supposed that the significance of glial reaction in epileptic brain might be unveiled by clarify the localization and degree of gliosis in epileptic mutant, Ihara epileptic rat. Possible function of microglia cells in the rat experienced epileptic seizures was studied by investigation of localization and degree of microglial reaction in IER brains with immunohitochemical examination using OX-42 antibody. Density of OX-42 positive microglial cells was investigated in the portions of cerebral cortex, endorrhinal cortex, thalamus, amygdale, hippocampus and dentate gyrus in IERs and non-epileptic control rats.In IERs, rats of 2 months old, microglial with OX-42 positive reaction was increased in mild or moderate degree in the portions of the brain described above, particularly in the hippocampus, the thalamus and the amygdala. In rats of 6 months and 10 months old, marked increase in OX-42 positive microglia was found in hippocampus, thalamus and amygdala in addition to the whole brain. Microglia cells with OX-42 positive reaction, which possessed short and thick processes, were thought to be an activated microglial of amoeboid type.It is suggested that microglial activation was induced by epileptic activities in the brain of IER, and then cytokines released by activated glial cells have some influences to the functions of neurons or glial cells. Because increased activated microglia was shown in the portions of hippocampus, thalamus and amygdala from young age, those areas ware thought to have significant role for the epileptogenesis. Furthermore, it is safely assumed that epileptic activities influenced not only in the hippocampus, thalamus and amygdala but also in other portions of the brain from the finding of diffuse increase in OX-42 positive cells in the whole brain of IER.